Dumbbell



FIG. 1 is a top perspective view of a dumbbell showing my new design according to a first embodiment;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a left side view thereof;

FIG. 5 is a right side view thereof;

FIG. 6 is a top view thereof;

FIG. 7 is a bottom view thereof;

FIG. 8 is a top perspective view of a dumbbell according to a second embodiment;

FIG. 9 is a front view thereof;

FIG. 10 is a rear view thereof;

FIG. 11 is a left side view thereof;

FIG. 12 is a right side view thereof;

FIG. 13 is a top view thereof; and,

FIG. 14 is a bottom view thereof.

The broken lines in the drawings illustrate the portions of the dumbbell, which form no part of the claimed design. 

CLAIM The ornamental design for a dumbbell, as shown and described. 